Refrigeration circulation and method of oil return



Sept. 25, 1956 A. a. NEWTON REFRIGERATION CIRCULATION AND METHOD OF OIL RETURN Filed Jan. 9; 1952 /////v/// r M INVENTOR ALWIN B- NEWTON #:44 4044 ATTORNEY United States Patent REFRIGERATION CIRCULATION AND METHOD OF OIL RETURN Alwin B. Newton, Jackson, Mich., assignor to Acme Industries, Inc., Jackson, Mich., a corporation of Michigan Application January 9, 1952, Serial No. 265,572

5 Claims. (Cl. 62-8) The present invention relates to improvements in the recirculation of refrigerant to effect increase in heat transfer rates.

In connection with the recirculation of refrigerant by mechanical means electrically driven pumps as well as injectors have been proposed. The principal objection to the electric pump is the cost of wiring and the electric motor. With respect to the injector, the proper return of oil to the compressor presents a diflicult problem. Also, with the injector complete separation of the evaporated gaseous refrigerant and the liquid which remains is essential.

According to the present invention, the wiring and motor cost of the electric pump and the limitations of the injector have been avoided by an arrangement whereby the refrigerant itself is employed to mechanically operate the pump to recirculate the refrigerant in the evaporator.

Thus, an object of the invention is to provide a novel arrangement for the recirculation of refrigerant in a heat exchanger.

Another object is concerned with an improved system of refrigerant recirculation and method of oil return in which the refrigerant containing a maximum oil concentration is withdrawn and used to pre-cool the liquid refrigerant.

Another object is to provide an improved system for refrigerant recirculation and oil return in which these results are accomplished without loss or addition of heat to the refrigeration system.

These and other objects and advantages of the present invention will more fully appear from a consideration of the following specification and the appended claims.

In the drawing the principles of the present invention are diagrammatically shown.

As illustrated, the high pressure refrigerant enters the system by the conduit under the control of the valve 12. The evaporator 14 is shown with tubes 16 supported in the tube sheet 18. A suitable manifold casing 20 has cavities 22, 24, 26 separated by partitions 28 for receiving refrigerant of one set of tubes 16 and returning the refrigerant to another set of tubes for the return flow, all in a well known manner.

To use as much energy from the refrigerant system and compressor as possible and improve the heat transfer while providing a reliable return of oil to the compressor from the point of maximum concentration in the evaporator, we propose to recirculate the refrigerant through the employment of a turbine driven pump. As shown, the high pressure refrigerant under the control of the valve 12 is directed against the blades of the turbine 30, preferably by a plurality of nozzles 32 connected to an annular distributor conduit 34. The turbine 30 has a shaft 36 upon which the centrifugal pump 38 is mounted.

In passing through the nozzles 32 and driving the turbine blades expansion and reduction in pressure of the liquid refrigerant takes place with a portion becoming ice gaseous as it leaves the turbine housing 40 and enters the conduit 42 which opens into the cavity 22 and from which the refrigerant is directed into the first set of tubes of the evaporator 14. The refrigerants sinuous course through the evaporator 14 takes place by the refrigerant being directed by the return set of tubes into the cavity 24 and back again into the following set of return tubes to eventually be discharged into the cavity 26. From this point the liquid and gaseous refrigerant is deflected by suitable separators 44 from the inlet 46 of the suction line 48 leading back to the compressor. From the separator 44, the gaseous refrigerant passes upwardly to the inlet 46 and the liquid refrigerant gravitates to the inlet chamber 50 of the pump 38. The discharge of liquid refrigerant from the pump 38 takes place through the inlet 52 opening into the conduit 42 where it joins the refrigerant from the turbine discharge and is recirculated.

As the refrigerant entering the pump from the inlet chamber 59 is the richest in oil it is advantageous to return the oil to the compressor by connecting lead line 54 to the compressor side of the pump at 56. A valve 53 controls the amount of oil-enriched refrigerant flowing in the line 54 to the heat exchanger 69 in heat exchange relation with the high-pressure refrigerant flowing in the line 10 from the compressor (not shown). With this arrangement, the heat from the high-pressure refrigerant in line 10 separates the oil and liquid refrigerant entering the heat exchanger 60 by converting the liquid refrigerant into gaseous refrigerant in which form the separated refrigerant and oil flows through the line 62 into the suction line 48 leading to the compressor.

Having thus described my invention what I claim as new and desire to cover by Letters Patent is:

1. In a refrigerant system having a source of highpressure liquid refrigerant, an evaporator, means for recirculating liquid refrigerant from said source through said evaporator including a pump, a turbine for driving said pump, means for directing high-pressure liquid refrigerant against said turbine to drive the same and means for directing the turbine actuating refrigerant from said turbine into said evaporator for re-circulation by said 2. In a refrigerant system as defined in claim 1, wherein said means for directing high pressure liquid refrigerant against said turbine includes means under the regulation of cooling demands of said heat exchanger for controlling the total flow of refrigerant to said turbine whereby the rate of operation of the turbine and the return of refrigerant re-circulation are controlled by the cooling demands.

3. In a refrigerant system having a source of high pressure liquid refrigerant and entrained oil, an evaporator, means for re-circulating liquid refrigerant and oil through said evaporator including a pump, a draw-off line for oil enriched recirculated refrigerant connected to the pressure side of said pump, means for separating the refrigerant and oil flowing in said line by evaporating the refrigerant and returning the separated oil and gaseous refrigerant to the high pressure source, said last means including a heat exchanger, valve means for regulating the flow of combined liquid refrigerant and oil to said heat exchanger to evaporate the refrigerant, and control means for said valve means associated with said heat exchanger and influenced by the gaseous refrigerant in the discharge from said heat exchanger.

4. A method of refrigerant supply and recirculation to a heat exchanger comprising the steps of supplying high pressure liquid refrigerant to the heat exchanger at a greater rate than it can be evaporated without recirculation, re-circulating the unevaporated refrigerant in the heat exchanger through a mechanical medium directing the entering high pressure liquid refrigerant against said medium as a source of energy to actuatesaid rnediurn for re-ci'rculating'the unevaporated refrigerant, and directing the discharge of liquid refrigerant from said medium into the discharge of said high pressure liquid refrigerant after extraction of energy therefrorn by said 5 medium for re-circul'ation' by" said medium.

5. A method as defined in 'cl'a'ir'n 4, Whereiri the demands of the heat exchanger simultaneously control the rate of the entering liquid refrigerant and the rate of recirculation through the step of controlling only the rate 10 of the entering liquid refrigerant.

References" Cited 'in the file of this patent UNITED STATES PATENTS Strong 1 Nov. 4, 1932 Phillips July 5, 1938 Consley June 17, 1941 Sanchez Feb. 5, 1946 Trumpler 1 Nov. 19, 1946 

